Description: This proposal will develop long, continuous, curved microchannel plates (MCPs) for use in spaceflight ion mass spectrometers. These instruments obtain ion mass in part by measuring the ion speed. Ions create secondary elections, first as they enter the instrument window, then as they ht a target. The flight time across the distance in between provides the speed. The time is measured by detecting secondary electrons from the window and then the target. Curved MCPs simplify the detection because: they have a cylindrical symmetry which is compatible with instrument fields of view; the MCP channels always have the same orientation to electron flight paths, and so create uniform azimuthal detection efficiency; and they may be placed close to the window and target, thereby improving time of flight and mass resolution. Curved MCPs will be developed starting with the successful Incom approach for flat MCPs. A glass capillary array is first formed with 20 micron pores. Using Atomic Layer Deposition, the array is then coated with thin films that create the desired resistance and gain.

Benefits: Mass spectrometers for upcoming missions IMAP, GDC and MEDICI will all benefit from curved MCPs, either for particle detection, or for UV detection. Prototyping efforts within research groups for upcoming proposals will also benefit from curved MCPs. Curved MCPs simplify secondary electron steering design for particle instruments, and allow more efficient use of interior detector volume. This improves performance, reduces design time and reduces instrument volume.

Terrestrial mass spectrometers often use magnetic fields to cause mass-dependent deflections of incoming particles. Some of these instruments use a linear array of detectors at a focal plane to measure the deflection. They can perform spectrometry simultaneously over a wide range of masses, without changing magnetic field strength. Instead of using an array of channeltron detectors, these instruments could use long, continuous, curved MCPs with a position-sensitive anode for maximum mass resolution. Positron emission tomography (PET) will benefit from curved MCPs in curved microchannel plate photomultiplier tubes. Curved MCP-PMTs will improve detection uniformity in the circular detection array surrounding the test subject. Incom is collaborating with Argonne, the University of Chicago, Fermilab and UC Berkeley to make a flat ,8" square MCP-PMT known as the Large Area Picosecond Photo-Detector (LAPPD). A curved version would benefit the PET application.